A Zero-day vulnerability refers to a security flaw in software or hardware that is unknown to the vendor or has not yet been patched. If this vulnerability is exploited before the vendor has issued a fix or patch, it becomes a Zero-day exploit. These attacks are highly dangerous because they take advantage of the absence of defenses due to the lack of awareness or mitigation options.
A). Spoofing is a form of impersonation, not necessarily tied to unpatched vulnerabilities.
B). Brute-force attacks rely on repeatedly guessing credentials and are not related to software flaws.
C). DoS (Denial of Service) attacks are meant to overwhelm systems and don ' t necessarily exploit unknown vulnerabilities.
Reference:
CompTIA A+ 220-1102 Objective 2.3: Compare and contrast common social engineering, threats, and vulnerabilities.
Study Guide Section: Threat types - Zero-day attacks, definitions, and implications

Multi-Factor Authentication (MFA) requires at least two different types of authentication factors:
Something you know (e.g., password or PIN)
Something you have (e.g., smartphone or hardware token)
Something you are (e.g., fingerprint or facial recognition)
Option A, sending a code to the user's phone, is an example of " something you have " - a physical device that receives a one-time passcode. Combined with a password, this forms a proper MFA implementation.
B). Date of birth is another knowledge-based factor (like a password), not a second factor type.
C). Solving a math problem is not a recognized authentication factor.
D). A PIN is also " something you know " and does not count as a distinct MFA factor when paired with a password.
Reference:
CompTIA A+ 220-1102 Objective 2.2: Compare and contrast common security measures and authentication technologies.
Study Guide Section: Authentication factors - password, biometrics, tokens, MFA

A "utility failure" means the building's AC power source has dropped out (blackout) or sagged severely, causing the workstation to lose power instantly and shut down. The best way to prevent an immediate shutdown during these events is an Uninterruptible Power Supply (UPS), which contains a battery and can continue supplying AC power long enough to keep the PC running briefly and allow a graceful shutdown.
Mike Meyers' Lab Manual states that a UPS "continues to supply AC power...during both brownouts and blackouts via a battery," preventing the computer from instantly losing power when the utility fails. Quentin Docter likewise explains that UPS devices protect against "power sags and even power outages," using stored battery energy so the administrator (or OS integration) can safely shut down rather than crash off.
A surge suppressor protects from spikes, not outages. A redundant PSU only helps if the PSU fails, and Docter notes it cannot keep a system running during a power outage. A line voltage regulator helps stabilize voltage but doesn't provide power when utility power is absent.
References: Quentin Docter - CompTIA A+ Complete Study Guide (UPS vs redundant PSU; UPS protects outages); Travis Everett & Andrew Hutz - CompTIA A+ All-in-One Exam Guide (UPS protects during sag
/outage with battery); Mark Soper - Mike Meyers' A+ Lab Manual (UPS supplies power during brownouts
/blackouts; surge suppressor limits spikes).

See explanation below.
Explanation:
Inbox mail 1 -Account Locked- Phishing - Report email to Information Security Inbox mail 2 -Share your feedback - Legitimate - Perform no additional actions Inbox mail 3 -Employee orientation - Legitimate - Perform no additional actions Inbox mail 4 -Security Update - Spam - Report email to Information Security Inbox mail 5 -Interview - Legitimate - Perform no additional actions
-

This scenario involves a mismatch in device time settings, which can affect synchronization and authentication across the network. Using a Network Time Protocol (NTP) server ensures all networked devices maintain accurate and synchronized clocks.
From Travis Everett - All-in-One Exam Guide:
"NTP servers keep all devices on a network in sync. This prevents time drift, which can cause authentication issues with domain logins, certificates, and applications." .